They lost a tense semi-final 22-14 against Warrington Wolves to miss out on a third Wembley trip in four years.
Hull battled hard in the rain and fought throughout in relentless rain at Bolton, trailing just 16-14 until the 79th minute.
But they wasted too many chances, not least when coughing up the ball after forcing a drop-out late on.
Radford said: "I'm very disappointed.
"They made the most of their kicking, far superior to how we did. Sometimes that's the difference between going to a final and not.
"I said all along there was nothing between the sides, they both went all out.
"But clutch plays are huge and the error on play two from that drop-out with three to go... if you don't make that you don't go to a final.
"The effort was outstanding, the performance was really good, but they were really good too.
"Now it's all our eggs in one basket (going for a Grand Final)."
Hull had beaten Warrington in the 2016 final and Wolves also lost the showpiece last year against Catalans Dragons.
But now they get to atone and coach Steve Price said: "It feels like we've been invited to a wedding, again, and we want to be brides not the bridesmaid.
"I always knew what we had and that showed what we are, we showed our fighting spirit.
"Our foundation has been that for 18 months and we showed it in spades.
"It was a brutal game, but we stayed up and never shied away from the opposition.
"Credit to Hull, it was see-saw, but they had a crack and I thought we showed a lot of pump today."